This invention relates to a novel liquid crystalline compound useful for display elements, and a liquid crystal composition containing the compound.
Liquid crystal substances and compositions thereof have been used for various display devices, making use of the dielectric anisotropy (hereinafter abbreviated to .DELTA..epsilon.) and the optical anisotropy (hereinafter abbreviated to .DELTA.n) in the liquid crystal phases of the above substances and compositions.
Liquid crystal display modes include electrically controlled birefringence mode (ECB mode), twisted nematic mode (TN mode), supertwisted birefringence effect mode (SBE mode), dynamic scattering mode (DS mode), guest-host mode, etc., corresponding to the electrooptical effect applied. Liquid crystal materials used for display devices should be provided with a combination of various characteristics such as a broad mesomorphic range, a low viscosity, a large positive .DELTA..epsilon. value or negative .DELTA..epsilon. value, no large change in various characteristics of display elements, particularly in the threshold voltage, over a broad temperature range, etc., depending on the display modes and also depending on various characteristics required for display elements.
At present, however, there is no single compound which is practically usable in the aspect of mesomorphic range, operating voltage and response properties. Thus, a mixture of several kinds of liquid crystal compounds, or a mixture of several kinds of liquid crystal compounds with a potentially liquid crystalline compound or a non-liquid crystal compound have been practically used.